NestJS NATS 请求-响应

使用 NestJS 框架与 NATS（可扩展消息传递系统）进行请求-响应通信是一种强大而灵活的方式。NestJS 提供了一个简单且易于使用的方法，使开发人员能够轻松地实现分布式系统。在本文中，我们将探讨如何使用 NestJS 和 NATS 实现请求-响应通信，并提供一个案例代码来帮助理解。

shell
$ npm install --save @nestjs/microservices
$ npm install --save node-nats-streaming

typescript
import { Module } from '@nestjs/common';
import { ClientsModule, Transport } from '@nestjs/microservices';
@Module({
  imports: [
    ClientsModule.register([
      {
        name: 'NATS_CLIENT',
        transport: Transport.NATS,
        options: {
          url: 'nats://localhost:4222',
        },
      },
    ]),
  ],
})
export class AppModule {}

typescript
import { Injectable } from '@nestjs/common';
import { ClientProxy, MessagePattern } from '@nestjs/microservices';
@Injectable()
export class UserService {
  constructor(private readonly client: ClientProxy) {}
  @MessagePattern('getUserById')
  async getUserById(id: number): Promise {
    const pattern = { cmd: 'getUserById' };
    const payload = { id };
    return this.client.send(pattern, payload).toPromise();
  }
}

typescript
interface User {
  id: number;
  name: string;
}

typescript
import { Injectable } from '@nestjs/common';
import { ClientProxy, MessagePattern } from '@nestjs/microservices';
@Injectable()
export class UserService {
  constructor(private readonly client: ClientProxy) {}
  @MessagePattern('getUserById')
  async getUserById(id: number): Promise {
    const pattern = { cmd: 'getUserById' };
    const payload = { id };
    return this.client.send(pattern, payload).toPromise();
  }
}

typescript
import { Controller, Get, Param } from '@nestjs/common';
import { UserService } from './user.service';
@Controller('users')
export class UserController {
  constructor(private readonly userService: UserService) {}
  @Get(':id')
  async getUserById(@Param('id') id: number): Promise {
    return this.userService.getUserById(id);
  }
}

typescript
import { Module } from '@nestjs/common';
import { ClientsModule, Transport } from '@nestjs/microservices';
import { UserController } from './user.controller';
import { UserService } from './user.service';
@Module({
  imports: [
    ClientsModule.register([
      {
        name: 'NATS_CLIENT',
        transport: Transport.NATS,
        options: {
          url: 'nats://localhost:4222',
        },
      },
    ]),
  ],
  controllers: [UserController],
  providers: [UserService],
})
export class AppModule {}